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Issue: 01/2016
Measurement of implant stability increment after internal and external sinus floor elevation using resonance frequency analysis

Introduction: This study aimed to investigate whether the secondary implant stability is significantly higher in regions in which an internal sinus floor elevation (ISFE) procedure has been carried out compared to those regions where an external sinus floor elevation technique (ESFE) was applied. In addition, it aimed to ascertain whether the increase in primary implant stability relative to secondary implant stability is higher in regions where primary stability was initially low. Resonance frequency analysis (RFA) was utilized to compare primary and secondary implant stability, as well as the increase in stability between implants inserted by ISFE and those inserted by ESFE procedures.

Material and methods: The study population included 39 patients (25 women, 14 men) at a mean age of 60.3±10.6 years. In total, 70 implants were inserted in the posterior maxilla region, 35 of these by internal and the other 35 by external sinus floor elevation technique. Immediately after insertion, the first measurement of primary stability was taken by RFA, using an Osstell device (Osstell, Gothenburg, Sweden). The second measurement was taken after an individually defined period at the point of re-entry.

Results: The implant stability measured by RFA at the point of implantation in the group with external sinus floor elevation was ISQ 65.6±6.9. In the group with internal sinus floor elevation, it was ISQ 68.9±1.4. The result shows a statistically significant difference (p=0.035). Implants in the group with internal sinus floor elevation showed a mean measurement of ISQ 74.5±1.7 after healing. Therefore, the secondary stability in this group was slightly lower than in the group with external sinus floor elevation, at ISQ 75.2±3.8.

This difference, however, is not statistically significant. The increase in stability was higher in the group with external sinus floor elevation (ISQ 9.6±5.2) compared to the group with internal sinus floor elevation (ISQ 5.6±1.2).

Discussion: Within the limits of the study it can be stated that the secondary implant stability in regions in which an internal sinus floor elevation procedure has been carried out is not significantly higher than in those regions where an external sinus floor elevation technique was applied. A higher increase in stability has been demonstrated in regions where primary stability was initially low, i.e. in the group of implants with external sinus floor elevation.

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Issue: 03/2016 - Eric André Noack - Peter Gehrke
Survival and complication rates of implant-supported CAD/CAM lithium-disilicate single crowns

Introduction: New digital technologies facilitate the fabrication of CAD/CAM lithium-disilicate crowns on teeth and implants. Due to the limited data available only little is known about the influence of the CAD/CAM process on the clinical complication rate of all-ceramic implant restorations. The aim of this cohort study was to retrospectively analyze the survival and the technical/biological complication rates of implant-supported fixed lithium disilicate ceramic single crowns, milled using a CAD/CAM system, and cemented on titanium abutments.

Material and Method: One hundred and ninety-two implants were placed in 91 patients (58 female and 33 male) and provided with single crowns after a mean healing period of 3.86 months.

Results: After a mean of 45.8 months, implant survival rate was 99.5%. Within the observation period of seven years the cumulative success rate and the cumulative survival rate of the prosthetic superstructure was 87.5% and 94.3% after a mean of 41.9 months, respectively. Loss of single crowns was recorded in 11 cases, of which 10 were caused by technical reasons. Four crowns were lost due to loosening of the abutment screw, and 3 were lost due to the actual abutment fracturing. Two more were lost because the entire crown fractured/major chipping at the crown margin and one crown had to be removed because of a prosthetic schedule change. Periimplantitis as a biological complication was recorded in 8 cases, from which one implant/single crown had to be removed due to major inflammation.

Conclusion: Based on the promising results of the study, CAD/CAM lithium disilicate ceramic single crowns are a valuable restorative alternative in implant therapy.

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Issue: 02/2016 - Dieter Edinger - Thorsten Schüppstuhl
Template guided surgery: no longer static, but dynamic through using the positioning device Rosy

Introduction: Previous template guided systems have the disadvantage that it is not possible to make a controlled intraoperative correction of the drilling position. Sometimes the radiograph shows only imprecisely the surface of bone with lower density. This leads to the fact that one cannot use the guidance template.

Material and methods: After exposure of the bone, by means of a marker pin attached to the guidance template the actual bone surface is indicated. The guidance template is removed from the mouth and inserted in the positioning device Rosy. The implant pointer of the positioning device is then guided through an iPad to the point marked by the pin. This preliminary implant position is then corrected through the superimposed CBCT. A corrected final guidance hole is bored in the template with the drill of the positioning device. All the settings are performed via an iPad, which improves the hygiene potential.

Results: The correction of a guidance template is possible within an acceptable time during the operation.

Conclusion: The system presented here helps in complex situations by providing controlled correction of the guidance template during the operation.

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Issue: 02/2016
The influence of various implant types on peri-implant bone loss – a retrospective radiological evaluation

Background: Preserving marginal bone is crucial for good esthetic and functional results with implant-supported prosthetic restorations. However, several authors have reported remodeling of crestal bone and bone loss during the early stages following implant placement.

Objective: The objective of the present retrospective study was to review marginal peri-implant bone loss using radiographs collected by a dental oral surgery practice over a period of up to 17 3/4 years. It was hypothesized that no difference in bone loss would be found between the various dental implant types. The influence of implant-specific design features, prosthetic restorations, and the implant/abutment connection were investigated.

Materials and Methods: In this retrospective study, post-operative and follow-up radiographs of patients who had received implants in a private oral and maxillofacial practice over a 17 3/4-year period were digitized. Peri-implant bone-level changes were measured, and descriptive statistics computed.

Results: The study included 569 patients ranging in age from 14.8 to 84.4 years who received a total of 1434 implants, of which 173 images (12.1%) were excluded because of lack of follow-up radiographs. A total of 3613 radiographs were taken of the remaining 1261 implants, which included 506 from Astra Tech Dental (40.1%), 558 from Camlog (44.3%), and 197 from DENTSPLY Friadent (15.6%). The measurements were distributed evenly among upper and lower jaws. Marginal bone loss decreased markedly after the first 2 years, and significantly (p0.05) more bone loss was found in the upper jaw (mean=0.91mm, SD=±1.37) than in the lower jaw (mean=0.79mm, SD=±1.60). Bone cavities were smallest at single-tooth sites (mean=0.74mm, SD=±1.39) and in edentulous lower jaws. They were significantly greater (p0.05) around implants supporting bridges (mean=0.96mm, SD=±1.54). Short and thin implants induced less bone loss than long and thick ones (p0.05). Implants that had been placed in augmented areas incurred more bone loss overall than others during the course of observation, but the type of augmentation was crucial. Examination of the individual implant types revealed the most significant differences (p0.05). Regardless of the type of load, superstructure, augmentation or location, Camlog implants exhibited the largest bone cavities (mean=1.25mm, SD=±1.49), followed by DENTSPLY Friadent implants (mean=1.16mm, SD=±1.69), and Astra Tech dental implants (mean=0.18mm, SD=±1.07).

Conclusion: The implant/abutment connector geometry appeared to significantly influence the progression of bone loss.

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